Esp Ltd Mh 250.
You're better off asking this question via the "Support > Contact Support" pull down at the top of the page. ESP monitors the forums, but doesn't actually do anything useful with them.
Well since the Tech Support at ESP seems pretty useless, here's a picture I found of the older EMG HZ pickups. From what I could gather, they're basically the same thing, and the same wiring scheme. The white wire should be connected with the black wire, and the green should go to the ground.
Otherwise, try e-mailing EMG. They're pretty useful when it comes to questions about their products.